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  <title>Getting Started with LLVM System for Microsoft Visual Studio</title>
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<div class="doc_title">
  Getting Started with the LLVM System using Microsoft Visual Studio
</div>

<ul>
  <li><a href="#overview">Overview</a>
  <li><a href="#quickstart">Getting Started Quickly (A Summary)</a>
  <li><a href="#requirements">Requirements</a>
    <ol>
      <li><a href="#hardware">Hardware</a>
      <li><a href="#software">Software</a>
    </ol></li>

  <li><a href="#starting">Getting Started with LLVM</a>
    <ol>
      <li><a href="#terminology">Terminology and Notation</a>
      <li><a href="#objfiles">The Location of LLVM Object Files</a>
    </ol></li>

  <li><a href="#tutorial">An Example Using the LLVM Tool Chain</a>
  <li><a href="#problems">Common Problems</a>
  <li><a href="#links">Links</a>
</ul>

<div class="doc_author">
  <p>Written by: 
    <a href="mailto:jeffc@jolt-lang.org">Jeff Cohen</a>
  </p>
</div>


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<div class="doc_section">
  <a name="overview"><b>Overview</b></a>
</div>
<!-- *********************************************************************** -->

<div class="doc_text">

  <p>The Visual Studio port at this time is experimental.  It is suitable for
  use only if you are writing your own compiler front end or otherwise have a
  need to dynamically generate machine code.  The JIT and interpreter are
  functional, but it is currently not possible to generate assembly code which
  is then assembled into an executable.  You can indirectly create executables
  by using the C back end.</p>

  <p>To emphasize, there is no C/C++ front end currently available.
  <tt>llvm-gcc</tt> is based on GCC, which cannot be bootstrapped using VC++.
  Eventually there should be a <tt>llvm-gcc</tt> based on Cygwin or MinGW that
  is usable.  There is also the option of generating bitcode files on Unix and
  copying them over to Windows.  But be aware the odds of linking C++ code
  compiled with <tt>llvm-gcc</tt> with code compiled with VC++ is essentially
  zero.</p>

  <p>The LLVM test suite cannot be run on the Visual Studio port at this
  time.</p>

  <p>Most of the tools build and work.  <tt>bugpoint</tt> does build, but does
  not work.  The other tools 'should' work, but have not been fully tested.</p>

  <p>Additional information about the LLVM directory structure and tool chain
  can be found on the main <a href="GettingStarted.html">Getting Started</a>
  page.</p>

</div>

<!-- *********************************************************************** -->
<div class="doc_section">
  <a name="quickstart"><b>Getting Started Quickly (A Summary)</b></a>
</div>
<!-- *********************************************************************** -->

<div class="doc_text">

<p>Here's the short story for getting up and running quickly with LLVM:</p>

<ol>
  <li>Read the documentation.</li>
  <li>Seriously, read the documentation.</li>
  <li>Remember that you were warned twice about reading the documentation.</li>

  <li>Get the Source Code
  <ul>
    <li>With the distributed files:
    <ol>
      <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
      <li><tt>gunzip --stdout llvm-<i>version</i>.tar.gz | tar -xvf -</tt>
      <i>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;or use WinZip</i>
      <li><tt>cd llvm</tt></li>
    </ol></li>

    <li>With anonymous Subversion access:
    <ol>
      <li><tt>cd <i>where-you-want-llvm-to-live</i></tt></li>
      <li><tt>svn co http://llvm.org/svn/llvm-project/llvm-top/trunk llvm-top
      </tt></li>
      <li><tt>make checkout MODULE=llvm</tt>
      <li><tt>cd llvm</tt></li>
    </ol></li>
  </ul></li>
  
  <li> Use <a href="http://www.cmake.org/">CMake</a> to generate up-to-date
    project files:
    <ul><li>This step is currently optional as LLVM does still come with a
    normal Visual Studio solution file, but it is not always kept up-to-date
    and will soon be deprecated in favor of the multi-platform generator
    CMake.</li>
    <li>If CMake is installed then the most simple way is to just start the
    CMake GUI, select the directory where you have LLVM extracted to, and
    the default options should all be fine.  The one option you may really
    want to change, regardless of anything else, might be the
    CMAKE_INSTALL_PREFIX setting to select a directory to INSTALL to once
    compiling is complete.</li>
    <li>If you use CMake to generate the Visual Studio solution and project
    files, then the Solution will have a few extra options compared to the
    current included one.  The projects may still be built individually, but
    to build them all do not just select all of them in batch build (as some
    are meant as configuration projects), but rather select and build just
    the ALL_BUILD project to build everything, or the INSTALL project, which
    first builds the ALL_BUILD project, then installs the LLVM headers, libs,
    and other useful things to the directory set by the CMAKE_INSTALL_PREFIX
    setting when you first configured CMake.</li>
    </ul>
  </li>

  <li>Start Visual Studio
  <ul>
    <li>If you did not use CMake, then simply double click on the solution
    file <tt>llvm/win32/llvm.sln</tt>.</li>
    <li>If you used CMake, then the directory you created the project files,
    the root directory will have an <tt>llvm.sln</tt> file, just
    double-click on that to open Visual Studio.</li>
  </ul></li>

  <li>Build the LLVM Suite:
  <ul>
    <li>Simply build the solution.</li>
    <li>The Fibonacci project is a sample program that uses the JIT.  Modify
    the project's debugging properties to provide a numeric command line
    argument.  The program will print the corresponding fibonacci value.</li>
  </ul></li>

</ol>

<p>It is strongly encouraged that you get the latest version from Subversion as
changes are continually making the VS support better.</p>

</div>

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<div class="doc_section">
  <a name="requirements"><b>Requirements</b></a>
</div>
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<div class="doc_text">

  <p>Before you begin to use the LLVM system, review the requirements given
  below.  This may save you some trouble by knowing ahead of time what hardware
  and software you will need.</p>

</div>

<!-- ======================================================================= -->
<div class="doc_subsection">
  <a name="hardware"><b>Hardware</b></a>
</div>

<div class="doc_text">

  <p>Any system that can adequately run Visual Studio .NET 2005 SP1 is fine.  
  The LLVM source tree and object files, libraries and executables will consume
  approximately 3GB.</p>

</div>

<!-- ======================================================================= -->
<div class="doc_subsection"><a name="software"><b>Software</b></a></div>
<div class="doc_text">

  <p>You will need Visual Studio .NET 2005 SP1 or higher.  The VS2005 SP1
  beta and the normal VS2005 still have bugs that are not completely
  compatible. VS2003 would work except (at last check) it has a bug with
  friend classes that you can work-around with some minor code rewriting
  (and please submit a patch if you do).  Earlier versions of Visual Studio
  do not support the C++ standard well enough and will not work.</p>
  
  <p>You will also need the <a href="http://www.cmake.org/">CMake</a> build
  system since it generates the project files you will use to build with.</p>

  <p>
  Do not install the LLVM directory tree into a path containing spaces (e.g.
  C:\Documents and Settings\...) as the configure step will fail.</p>

</div>

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<div class="doc_section">
  <a name="starting"><b>Getting Started with LLVM</b></a>
</div>
<!-- *********************************************************************** -->

<div class="doc_text">

<p>The remainder of this guide is meant to get you up and running with
LLVM using Visual Studio and to give you some basic information about the LLVM
environment.</p>

</div>

<!-- ======================================================================= -->
<div class="doc_subsection">
  <a name="terminology">Terminology and Notation</a>
</div>

<div class="doc_text">

<p>Throughout this manual, the following names are used to denote paths
specific to the local system and working environment.  <i>These are not
environment variables you need to set but just strings used in the rest
of this document below</i>.  In any of the examples below, simply replace
each of these names with the appropriate pathname on your local system.
All these paths are absolute:</p>

<dl>
    <dt>SRC_ROOT</dt>
    <dd><p>This is the top level directory of the LLVM source tree.</p></dd>

    <dt>OBJ_ROOT</dt>
    <dd><p>This is the top level directory of the LLVM object tree (i.e. the
        tree where object files and compiled programs will be placed.  It is
        fixed at SRC_ROOT/win32).</p></dd>
</dl>

</div>

<!-- ======================================================================= -->
<div class="doc_subsection">
  <a name="objfiles">The Location of LLVM Object Files</a>
</div>

<div class="doc_text">

  <p>The object files are placed under <tt>OBJ_ROOT/Debug</tt> for debug builds
  and <tt>OBJ_ROOT/Release</tt> for release (optimized) builds.  These include
  both executables and libararies that your application can link against.</p>

  <p>The files that <tt>configure</tt> would create when building on Unix are
  created by the <tt>Configure</tt> project and placed in
  <tt>OBJ_ROOT/llvm</tt>.  You application must have OBJ_ROOT in its include
  search path just before <tt>SRC_ROOT/include</tt>.</p>

</div>

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<div class="doc_section">
  <a name="tutorial">An Example Using the LLVM Tool Chain</a>
</div>
<!-- *********************************************************************** -->

<div class="doc_text">

<ol>
  <li><p>First, create a simple C file, name it 'hello.c':</p>

<div class="doc_code">
<pre>
#include &lt;stdio.h&gt;
int main() {
  printf("hello world\n");
  return 0;
}
</pre></div></li>

  <li><p>Next, compile the C file into a LLVM bitcode file:</p>

<div class="doc_code">
<pre>
% llvm-gcc -c hello.c -emit-llvm -o hello.bc
</pre>
</div>

      <p>This will create the result file <tt>hello.bc</tt> which is the LLVM
         bitcode that corresponds the the compiled program and the library
         facilities that it required.  You can execute this file directly using
         <tt>lli</tt> tool, compile it to native assembly with the <tt>llc</tt>,
         optimize or analyze it further with the <tt>opt</tt> tool, etc.</p>
      
      <p><b>Note: while you cannot do this step on Windows, you can do it on a
         Unix system and transfer <tt>hello.bc</tt> to Windows.  Important:
         transfer as a binary file!</b></p></li>

  <li><p>Run the program using the just-in-time compiler:</p>
      
<div class="doc_code">
<pre>
% lli hello.bc
</pre>
</div>

      <p>Note: this will only work for trivial C programs.  Non-trivial programs
         (and any C++ program) will have dependencies on the GCC runtime that
         won't be satisfied by the Microsoft runtime libraries.</p></li>

  <li><p>Use the <tt>llvm-dis</tt> utility to take a look at the LLVM assembly
      code:</p>

<div class="doc_code">
<pre>
% llvm-dis &lt; hello.bc | more
</pre>
</div></li>

  <li><p>Compile the program to C using the LLC code generator:</p>

<div class="doc_code">
<pre>
% llc -march=c hello.bc
</pre>
</div></li>

  <li><p>Compile to binary using Microsoft C:</p>

<div class="doc_code">
<pre>
% cl hello.cbe.c
</pre>
</div>

    <p>Note: this will only work for trivial C programs.  Non-trivial programs
      (and any C++ program) will have dependencies on the GCC runtime that won't
      be satisfied by the Microsoft runtime libraries.</p></li>

  <li><p>Execute the native code program:</p>

<div class="doc_code">
<pre>
% hello.cbe.exe
</pre>
</div></li>
</ol>

</div>

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<div class="doc_section">
  <a name="problems">Common Problems</a>
</div>
<!-- *********************************************************************** -->

<div class="doc_text">

  <ul>
    <li>In Visual C++, if you are linking with the x86 target statically, the
    linker will remove the x86 target library from your generated executable or
    shared library because there are no references to it. You can force the
    linker to include these references by using
    <tt>"/INCLUDE:_X86TargetMachineModule"</tt> when linking. In the Visual
    Studio IDE, this can be added in
<tt>Project&nbsp;Properties->Linker->Input->Force&nbsp;Symbol&nbsp;References</tt>.
    </li>
  </ul>

<p>If you are having problems building or using LLVM, or if you have any other
general questions about LLVM, please consult the <a href="FAQ.html">Frequently
Asked Questions</a> page.</p>

</div>

<!-- *********************************************************************** -->
<div class="doc_section">
  <a name="links">Links</a>
</div>
<!-- *********************************************************************** -->

<div class="doc_text">

<p>This document is just an <b>introduction</b> to how to use LLVM to do
some simple things... there are many more interesting and complicated things
that you can do that aren't documented here (but we'll gladly accept a patch
if you want to write something up!).  For more information about LLVM, check
out:</p>

<ul>
  <li><a href="http://llvm.org/">LLVM homepage</a></li>
  <li><a href="http://llvm.org/doxygen/">LLVM doxygen tree</a></li>
  <li><a href="http://llvm.org/docs/Projects.html">Starting a Project
      that Uses LLVM</a></li>
</ul>

</div>

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  <a href="mailto:jeffc@jolt-lang.org">Jeff Cohen</a><br>
  <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
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